1. Field of the Invention
This invention relates to an electro-luminescence display (ELD), and more particularly to an organic electro-luminescence display device and a fabricating method thereof that are adaptive for preventing a deterioration of light-emission efficiency and picture quality.
2. Description of the Related Art
Recently, there have been developed various flat panel display devices reduced in weight and bulk that is capable of eliminating disadvantages of a cathode ray tube (CRT). Such flat panel display devices include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP) and an electro-luminescence (EL) display, etc.
There have been actively processed studies for attempting to make a high display quality and a large-dimension screen of the flat panel display device. In such flat panel display devices, the EL display device is a self-luminous device capable of light-emitting for himself. The EL display device excites a phosphorous material using carriers such as electrons and holes, thereby displaying a video image.
The EL display device is largely classified into an inorganic EL display device and an organic EL display device depending upon the used material.
Since the organic EL display device is driven with a lower voltage (i.e., about 5 to 20V) than the inorganic EL display device requiring a high voltage of 100 to 200V, it permits a direct current low voltage driving. Also, since the organic EL display device has excellent characteristics such as a wide viewing angle, a fast response and a high contrast ratio, etc., it can be used for a pixel of a graphic display, or a pixel of a television image display or a surface light source. Further, the organic EL display device is a device suitable for a post generation flat panel display because it has a thin thickness, a light weight and an excellent color sense.
FIG. 1 is a schematic view showing a structure of a general organic EL display device, and FIG. 2 is a detailed plan view of a portion (A area) in FIG. 1. FIG. 3 is a section view of the portion of the organic El display device taken along the I-I′ and II-II′ lines in FIG. 2.
Referring to FIG. 1 to FIG. 3, the related art EL display device includes a display area P1 provided with an organic EL array having driving electrodes (e.g., an anode electrode and a cathode electrode), etc., and a non-display area P2 provided with a pad portion 25 for applying driving signals to the driving electrodes at the display area P1. The display area P1 is provided with an anode electrode 4 formed on a substrate 2, and a cathode electrode 12 formed in a direction crossing the anode electrode 4.
A plurality of anode electrodes 4 are provided on the substrate 2 in such a manner to be spaced at a desired distance from each other. An insulting film 6 having an aperture for each EL cell area is formed on the substrate 2 provided with the anode electrode 4. On the insulating film 6, a barrier rib 8 for making a separation of an organic light-emitting layer 10 and a cathode electrode 12 to be formed thereon is provided. The barrier rib 8 is formed in a direction crossing the anode electrode 4, and has an overhang structure in which the upper portion thereof has a larger width than the lower portion thereof. The organic light-emitting layer 10 made from an organic compound and the cathode electrode 12 are entirely deposited onto the insulating film 6 provided with the barrier rib 8. The organic light-emitting layer 10 is formed by depositing a hole carrier layer, a light-emitting layer and an electron carrier layer onto the insulating film 6.
The non-display area P2 is provided with a first line 54 extended from the anode electrode 4 at the display area P1, data pads for supplying data voltages, via the first line 52, to the anode electrode 4, a second line 52 connected to the cathode electrode 12, and scan pads for supplying scan voltages via the second line 52. Herein, the second line 52 consists of a double layer having a transparent conductive layer 52a and an opaque conductive layer 52b. The data pad is connected to a tape carrier package (TCP) mounted with a first driving circuit for generating data voltages to thereby supply the data voltage to each anode voltage 4. The scan pad is provided at each side of the data pad. The scan pad is connected to a TCP mounted with a second driving circuit for generating scan voltages to thereby supply the scan voltage to each cathode electrode 12.
The organic EL array at the display area P1 has a characteristic liable to be deteriorated against moisture and oxygen. In order to overcome this problem, an encapsulating process is carried out to join the substrate 2 provided with the organic EL array of the anode electrode 2, etc. with a cap 28 by a sealant 25 such as an epoxy resin. A getter for absorbing the moisture and oxygen is filled into the rear center portion of the cap 28 to thereby protect an organic EL array from the oxygen and moisture.
In the related art organic EL display device having the structure as mentioned above, as shown in FIG. 4, if a voltage is applied between the anode electrode 4 and the cathode electrode 12, then electrons (or cathodes) generated from the cathode electrode 12 are moved, via an electron injection layer 10a and an electron carrier layer 10b, into a light-emitting layer 10c. On the other hand, holes (or anodes) generated from the anode electrode 4 are moved, via a hole injection layer 10d and a hole carrier layer 10e, into the light-emitting layer 10c. Thus, electrons and holes fed from the electron carrier layer 10b and the hole carrier layer 10e are collided with each other to be re-combined at the light-emitting layer 10c, thereby generating a light. This light is emitted into the exterior via the anode electrode 4, thereby displaying a picture.
Meanwhile, in such an organic EL display device, the sealant 25 may be frequently flown, via between the barrier rib 8 and the barrier rib 8, into the organic EL array of the display area P1 when the cap 28 is joined with the cap 2. The sealant 25 contains a large amount of moisture, oxygen and impurity to cause a damage to the organic light-emitting layer 10 of the organic EL array. Therefore, there is raised a problem in that a light-emission efficiency and a picture quality are deteriorated.